Technical Advisory Board

Michael G. Nelson, Ph. D

Professor of Mining Engineering, University of Utah, Salt Lake City, Utah

Dr. Nelson is a Professor of Mining Engineering at the University of Utah. He was the Department Chair from 2008 to 2019. He also taught as a Professor of Mining Engineering at the University of Alaska, Fairbanks from 1989 to 1995. He has taught courses covering an extensive range of topics related to mining engineering, underground mining, mine design, mining investment analysis, applied statistical analysis, and mine safety. Dr. Nelson has conducted numerous research projects and has an extensive list of published articles and books.

Dr. Nelson has also had broad experience working in the mining industry. He served as Director of Research and Process Engineering, Baker-Hughes Process Equipment Company, Senior Vice President of Technology and Director, Palladon Ventures, LLC, Managing Partner of Magpie Minerals, Inc., President and Chief Engineer of Alaska Mining Services, Director of Fairbanks Exploration Company, and Senior Research Engineer at Consolidation Coal Company. Dr. Nelson has been on the cutting edge of the development and implementation of new technologies for the mining and mineral processing industries.

Dr. Nelson is a joint holder of nine patents. He has received a number of awards and honors from the mining industry and mining industry associations.

Dr. Nelson brings extensive experience in mining, mine development, mineral processing technology, and mine safety, as well as a wealth of experience in the business aspects of the mineral development industry to the Sierra Minerals' Board of Technical Advisors.

D. Erik Spiller

Research Professor, Metallurgical and Materials Engineering Colorado School of Mines Golden, Colorado

Mr. Spiller a Research Professor at the Colorado School of Mines, with an emphasis on metallurgical processes, study, and research. His technical expertise includes ore processing from liberation by crushing and grinding through beneficiation using various physicochemical techniques based on particle size, specific gravity, surface chemistry (flotation), conductivity, magnetic susceptibility, leaching, and liquid/solid separation. Mr. Spiller is recognized as a world-class expert in these technologies on which he lectures as a Research Professor (full-time appointed faculty) at the Colorado School of Mines.

Mr. Spiller has extensive mining industry experience including past positions as Vice President and Principal Metallurgist with Tetra Tech’s Global Mining Practice, Vice President and a rotating member of the Office of President at Hazen Research, President and Chairman of A.R. MacPherson Consultants, Ltd., Director of Metallurgical Services for Newmont Mining Company, General Manager of the Mineral Processes Division at Washington Group International (now AECOM), and Vice President of Operations for Outokumpu Physical Separation.

Mr. Spiller is a Mining and Metallurgical Society of America Qualified Professional (QP) as well as a Registered Qualified Professional by the Society of Mining, Metallurgy and Exploration (SME).

Mr. Spiller brings to Sierra Minerals, LLC extensive experience in mineral processing, mining, and the management of mining and mineral industry enterprises to the Sierra Minerals’ Board of Technical Advisors.

Tommy B. Thompson, Ph. D.

Professor Emeritus and Former Director of the Center for Research in Economic Geology University of Nevada, Reno Qualified Professional Geologist Reno, Nevada

Dr. Thompson is Professor Emeritus of Economic Geology, Department of Geological Sciences & Engineering in the Mackay School of Earth Sciences & Engineering, University of Nevada, Reno. Dr. Thompson is a Qualified Person per NI-43-101 requirements by the American Institute of Professional Geologists – CPG#10875, and a Registered Member #3223450 of the Society of Mining, Metallurgy & Exploration.

Dr. Thompson was the former and founding Director of the Ralph Roberts Center for Research in Economic Geology (CREG) at the University of Nevada, Reno. In this position, he worked closely with mining industry leaders who sponsored research projects for his graduate advisees.

Dr. Thompson has an extensive geological consulting practice. He has consulted for over thirty companies in the United States, Central and South America, Ireland, Australia, and New Zealand. Clients included Newmont Mining Corporation, ASARCO, Inc., Placer Dome, (USA), Barrick Goldstrike Mines, Inc., Kennecott, BHP, Tahoe Resources, etc. He has authored more than 70 articles in professional geology journals, presented numerous papers on geology and geological structures at various mining and geological society meetings, and has conducted professional development courses for major mining companies in the US, Mexico, Perú, and Argentina, both in English and Spanish.

Dr. Thompson brings extensive knowledge and experience in economic geology, ore structures, geological exploration, and the effective management of geological exploration to the Sierra Minerals’ Technological Advisory Board.